Apple's iPhone 3GS, the last iPhone to go with a plastic back. For now.
Apple

Apple's next iPhone might not be the only thing to get a plastic model.

A new job listing posted on Tuesday, and spotted by 9to5Mac, shows that the company's looking to bring on a new senior materials engineer to its iPhone and iPad materials team to create new plastic parts.

Apple already uses plastic within its devices, though the listing suggests the company's looking to expand the role it plays in those two devices.